1. Technical Field
An improved dispensing system and a process for dispensing various liquids of a dispensing system are shown and described. More specifically, an improved dispensing system is disclosed for combining multiple liquids and/or slurries of a liquid formulation whereby the multiple liquids include one or more base fluids which constitute a majority of the formulation and which can be dispensed by weight (i.e. gravimetrically) because the exact amount of such base ingredients is not important and further whereby the formulation includes smaller amounts of additives which must be dispensed precisely and, accordingly, are dispensed precisely by volume using the disclosed dispenser. The dispensing system includes a scale for measuring the amount of base materials added and a plurality of nutating pumps for accurately dispensing smaller amounts of additives. A controller is used to control the operation of valves through which the base materials are dispensed and for controlling the operation of the nutating pumps which dispense the smaller amounts of the various additives. An improved valve arrangement, stepper motor valve actuator and control mechanism for the gravimetric dispensing of base or bulk materials are disclosed.
2. Description of the Related Art
A number of liquid products such as inks, dyes, cosmetic lotions and paints are fabricated from a plurality of different liquids and/or slurries which include base materials or solvents and special additives such as colorants or tints or functional additives that affect the property of the liquid or slurry product.
Throughout this specification, the term “liquid” is meant to encompass slurries, pastes and other materials capable of being pumped. Various dispensers are known for dispensing the various ingredients of a liquid product into a container. Some of these dispensers are more accurate than others and some of these dispensers operate mote quickly than others. While the following discussion will be directed toward the formulation of paints, it will be noted that this application and the dispensers and methods of dispensing disclosed herein are applicable to various fields beyond that of paints and this disclosure generally applies to liquid formulations which consist of relatively large quantities of base materials or solvents or water and relatively small quantities of additives such as tints or colorants or other functional ingredients that must be added with precision.
Turning to the field of paints, it will be noted that paints are made in a vast number of different colors and shades of colors. Each specific paint color has a specific formula of components to provide the desired color. A paint formula generally includes a relatively large amount of a base component and smaller amounts of one or more colorants. Each colorant is measured according to the formula and dispensed from a bulk colorant supply, added to the base, and then mixed to produce the desired paint color.
Typically, the base material is pre-formulated and, in the retail environment, colorants are added to the paint by an existing colorant dispenser. Thus, the base is formulated separately and dispensed separately from the colorants. For example, U.S. Pat. No. 6,221,145 discloses a method of preparing base formulations for paints. The '145 patent teaches a method for preparing various base formulations at a retail store so paints can be sold with a specific use in mind, such as a flat base for walls, a high gloss base for wood and trim or other applications such as floors, concrete, etc.
To utilize the technology disclosed in the '145 patent a separate dispensing apparatus must be used to prepare the base formulation and a separate apparatus must be used to dispense the colorants because of the vastly different quantities used for the base materials and the colorants. Specifically, the base materials may be added by weight or maybe estimated by the technician who has some skill or experience. However, the colorants must be added very precisely as a one milliliter or less error in the amount of colorant can produce a noticeable error in the color of the paint product.
Fluid dispensing apparatuses exist that dispense formulations using an analog signal that is proportional to the amount the dispensing valve needs to be opened in order to produce a predetermined flow rate. For a large dispense of base materials, a high amplitude analog signal is used to move the dispense valve to a fully open position The analog signals are converted into a linear motion to open or close a dispensing valve as needed. In the past, this has been achieved by connecting the analog signal to a voltage to pneumatic pressure converter and applying the air pressure to an air cylinder connected to the dispensing valve. Such an air cylinder works against a spring inside the dispensing valve. While this system functions, it does not accurately reproduce the required flow rate from a given analog signal if the system is not calibrated accurately or frequently. This results in slow or inaccurate dispenses which have to be corrected by frequent adjustments to the calibration data. Thus, a need exists for an accurate and efficient method of opening and closing the base formulation dispensing valves.
Existing colorant dispensers have been used in retail paint supply stores and hardware stores. For example, existing colorant dispensing equipment has included manual and automated machines. Automated colorant dispensing equipment can include several bulk colorant containers, in which each colorant container is connected to an inlet of a fluid pump. The outlet of the fluid pump is connected to a 3-way valve which has a dispense outlet connected to a dispense nozzle and a by-pass outlet connected to a recirculation fluid line. Either one motor may drive all pumps or several pumps may be driven by a single motor through a common drive mechanism or each pump may be driven by an individual motor. When an amount of colorant is dispensed, the motor drives the pumps and the 3-way valve for the particular colorant is opened to allow the colorant to be dispensed through the nozzle. The time period that the valve remains open determines the amount of colorant dispensed. The other 3-way valves, which are all being simultaneously driven by the motor, are in a by-pass mode so that the colorant recirculates back into its container rather than being undesirably dispensed.
Other paint colorant dispensers utilize a nutating pump and a computer control system to control the pump. Nutating pumps have a piston which is positioned inside of a housing having a fluid inlet and a fluid outlet. The piston simultaneously slides axially and rotates inside of the housing. Existing nutating pumps have been operated by rotating the piston through a full 360° rotation and corresponding linear travel of the piston. Such piston operation results in a specific amount of fluid pumped by the nutating pump with each revolution. Accordingly, the amount of fluid pumped for any given nutating pump is limited to multiples of the specific volume. If a smaller volume of fluid is desired, then a smaller sized nutating pump is used or manual calibration adjustments are made to the pump.
For example, in paint colorants, a minimum dispense can be about 1/256 of a fluid ounce. U.S. Pat. Nos. 6,540,486 and 6,398,513 disclose improvements to nutating pump technology which provide for mote accurate dispensing of paint colorants and other fluids such as hair dyes and cosmetics applications. Both of these patents are commonly assigned with this application and are incorporated herein by reference.
While nutating pump technology has beneficial applications for the dispensing of relatively small quantities of liquids such as colorants and functional additives to a liquid formulation, nutating pumps lack the speed of other types of pumps and therefore are inefficient in terms of time when it comes to dispensing base materials and solvents. Thus, notwithstanding the developments disclosed in U.S. Pat. No. 6,221,145, many paint retailers prefer to carry pre-packaged bases to which they only need to add colorants by way of one of the currently available colorant dispensing machines. The reason being is that paint retailers are unwilling or unable to devote the amount of space that would be required to house two separate dispensing machines, one for base materials and one for colorants.
Specifically, currently available colorant dispensers are quite large due to the necessity of the cabinet housing a plurality of colorant canisters, such as eight or more (twelve preferably) and a separate pump for each canister. The bulkiness of the colorant dispenser is exacerbated by the need to include a controller, such as a central processing unit, a keyboard and a monitor and cabinet space to house these items. Further, some dispensers must include a large number of different colorants (in excess of twenty) thereby increasing the size of the cabinet that holds the canisters.
Because each store or retail facility is designed differently, many retailers are faced with the difficult task for making room for such large automated paint colorant dispensers in areas of limited space. As a result, there is a need for a more flexible design for automated paint colorant dispensers which would enable the configuration of these dispensers to be easily altered, depending upon the facility in which they are to be installed. The use of a separate machine to carry out the processes of the '145 patent would also be very problematic and would not be well received by merchants with limited floor space.
Further, most automated paint colorant dispensers are designed to dispense paint colorants into a large, five gallon pail or container. As a result, the shelf that supports the container is disposed vertically below the dispense outlet a sufficient distance so as to permit a five gallon container to be disposed on top of the supporting shelf but below the dispense outlet or nozzle. However, paint retailers also mix and sell paints in smaller quantities such as single gallons, quarts and pints. When a retailer needs to custom mix a smaller quantity of paint using an automated dispenser designed to dispense colorants into larger five gallon containers, a smaller container is disposed so far below the dispense outlet that splashing of the colorant as it reaches the smaller container is common and problematic. Obviously, when the colorant splashes outside of the container, the accuracy of the resulting paint color is compromised. Further, splashing of paint colorant outside of the container receptacle also results in colorant being splattered onto the dispensing apparatus causing it to be unsightly and in need of frequent cleaning. Thus, there is a need for an improved paint colorant dispenser design which enables the dispenser to easily accommodate large and small containers to thereby eliminate the splashing problem.
Therefore, there is a need for an improved fluid dispensing apparatus which is capable of quickly and efficiently dispensing large quantities of materials such as base materials or solvents, and which can quickly, efficiently, and accurately dispense small quantities of material such as tints, colorants or other additives. It would be very desirable to combine both of these very different functions in a single, compact machine that has a flexible design which enables the machine to be installed in a variety of different floor plans. Further, such an improved machine should preferably be able to accommodate containers of various sizes without the dripping problems associated with prior art machines.